Luo Hongchun, Ji Honglan, Chen Zijian, Liu Bin, Xue Zhongshu, Li Zhijun
College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot, 010018, China.
Collaborative Innovation Center for Integrated Management of Water Resources and Water Environment in the Inner Mongolia Reach of the Yellow River, Hohhot, 010018, China.
Sci Rep. 2025 Jan 14;15(1):1912. doi: 10.1038/s41598-025-85884-5.
This study investigates the critical impact of incipient sediment motion on sediment transport estimation and riverbed evolution prediction. In this research, we examine the effects of ice cover on the vertical distribution of flow velocity, establishing a mathematical relationship between the vertical average flow velocities in open channel and ice-covered flows. This leads to the derivation of a formula for incipient motion velocity under ice cover. Additionally, the study analyzes the riverbed evolution process under ice jam conditions. The proposed formula is applicable to both open channel and ice-covered flows, effectively capturing the characteristics of incipient sediment motion for non-cohesive and cohesive sediments. The calculated incipient motion velocities closely align with the empirical data from existing literature. The study reveals that the roughness of ice cover significantly influences the incipient motion velocity of sediment, with higher ratios of ice cover roughness to riverbed roughness promoting sediment initiation under more favorable hydraulic conditions. Furthermore, the riverbed beneath ice jams experiences significant scouring. Field observations indicate that when ice jams form in localized sections of the river, the displacement of the main flow can substantially increase flow velocity in areas away from the ice jam, leading to scouring in non-ice-jammed areas and sedimentation in ice-jammed areas. The uneven distribution of ice jam is likely a critical factor contributing to discrepancies between theoretical predictions and observed outcomes. The complexity and limited data associated with the initiation of cohesive sediments pose challenges in validating the proposed formula for these sediment types.
本研究探讨了初期泥沙运动对泥沙输运估算和河床演变预测的关键影响。在本研究中，我们研究了冰盖对流速垂直分布的影响，建立了明渠水流和冰盖水流中垂直平均流速之间的数学关系。由此推导出了冰盖下初期运动速度的公式。此外，该研究分析了冰塞条件下河床的演变过程。所提出的公式适用于明渠水流和冰盖水流，有效地捕捉了非粘性和粘性泥沙初期泥沙运动的特征。计算得到的初期运动速度与现有文献中的经验数据密切吻合。研究表明，冰盖粗糙度对泥沙的初期运动速度有显著影响，冰盖粗糙度与河床粗糙度的比值越高，在更有利的水力条件下越有利于泥沙起动。此外，冰塞下的河床会经历显著冲刷。现场观测表明，当河流局部河段形成冰塞时，主流的位移会大幅增加冰塞以外区域的流速，导致非冰塞区域冲刷和冰塞区域淤积。冰塞分布不均可能是导致理论预测与观测结果存在差异的关键因素。粘性泥沙起动相关的复杂性和有限数据给验证这些泥沙类型的所提出公式带来了挑战。
